Dp ship seawater variable frequency central fresh water cooling system and control method thereof

Abstract

The application belongs to the technical field of ship cooling system, and discloses a DP ship seawater variable frequency central fresh water cooling system and a control method thereof. The system comprises a control device and a plurality of DP chain cooling units corresponding to a plurality of DP chains. Each DP chain cooling unit comprises a variable frequency seawater pump, a seawater collecting header and a plurality of independent fresh water cooling circuits, each of which comprises a fresh water cooling pump and a central cooler. The variable frequency seawater pump is connected to the plurality of central coolers through seawater supply branches; the seawater outlets of the central coolers are connected to the seawater collecting header, and each of the central coolers is provided with a first temperature detection member, and the seawater collecting header is provided with a second temperature detection member. The control device adjusts the opening of the corresponding flow regulating valve according to the detection temperature of each first temperature detection member, and adjusts the rotating speed of the variable frequency seawater pump according to the detection temperature of the second temperature detection member. The application can improve the cooling independence, adapt the seawater supply to the cooling load change, and reduce the operation energy consumption.

Description

Technical Field

[0001] This invention relates to the field of marine cooling system technology, and in particular to a DP marine seawater variable frequency central freshwater cooling system and its control method. Background Technology

[0002] DP vessels are typically equipped with multiple relatively independent DP chains. Each DP chain includes a main generator, propulsion equipment, frequency converter, transformer, and related auxiliary equipment. These devices generate heat during operation, which requires cooling through a central freshwater cooling system to ensure stable operation.

[0003] In existing DP (Dual Density) vessels' central freshwater cooling systems, multiple cooling users within a single DP chain are typically connected to the same freshwater cooling loop. When a freshwater cooling pump, central cooler, or pipeline in this loop fails, it can easily affect multiple cooling users simultaneously, making it difficult to meet the relatively independent cooling needs of different users.

[0004] Furthermore, the operating loads and heat dissipation requirements of different cooling users may vary significantly. When multiple central coolers are supplied with seawater by a centralized seawater pump, it is difficult to balance the actual cooling load of each central cooler if only the total seawater flow is uniformly regulated. This can easily lead to situations where some central coolers have insufficient seawater flow while others have excessive seawater flow. If the seawater pump operates at a high flow rate for an extended period, it will result in unnecessary energy consumption.

[0005] Therefore, there is an urgent need to provide a DP ship seawater variable frequency central freshwater cooling system to improve the cooling independence between different cooling users and enable the seawater supply to adapt to the changes in the cooling load of each central cooler and the overall DP chain, thereby reducing the system's operating energy consumption. Summary of the Invention

[0006] One object of the present invention is to provide a DP ship seawater variable frequency central freshwater cooling system to improve the cooling independence between different cooling users and to enable the seawater supply to adapt to changes in the cooling load of each central cooler and the overall DP chain.

[0007] To achieve this objective, the present invention adopts the following technical solution: This invention provides a variable frequency central freshwater cooling system for DP (DP) vessels, used in DP vessels with multiple DP chains. The system includes a control device and multiple DP chain cooling units corresponding to each of the multiple DP chains. Each DP chain cooling unit includes a variable frequency seawater pump, a seawater manifold, and multiple independently configured freshwater cooling circuits. Each freshwater cooling circuit is connected to a group of cooling users and includes a freshwater cooling pump and a central cooler. The outlet of the freshwater cooling pump is connected to the water supply side of the corresponding group of cooling users. The central cooler has a freshwater channel and a seawater channel for mutual heat exchange. The freshwater channel is connected to the corresponding freshwater cooling circuit. The outlet of the variable frequency seawater pump is connected to multiple seawater supply branches, and these multiple seawater supply branches are connected to the multiple central coolers. In a one-to-one correspondence, each seawater supply branch is connected to the inlet of the seawater channel of the corresponding central cooler, and each seawater supply branch is equipped with a flow regulating valve; the outlet of the seawater channel of each central cooler is connected to the seawater collection manifold of the same DP chain cooling unit, and each seawater channel outlet is equipped with a first temperature sensor, and the seawater collection manifold is equipped with a second temperature sensor; the control device is communicatively connected to each of the variable frequency seawater pumps, each of the flow regulating valves, each of the first temperature sensors, and each of the second temperature sensors, and the control device is configured to adjust the opening of the corresponding flow regulating valve according to the detected temperature of each of the first temperature sensors, and to adjust the speed of the corresponding variable frequency seawater pump according to the detected temperature of each of the second temperature sensors.

[0008] Optionally, it also includes a backup variable frequency seawater pump shared by multiple DP chain cooling units; the outlet of the backup variable frequency seawater pump is connected to multiple backup water supply branches, and the multiple backup water supply branches correspond one-to-one with the multiple DP chain cooling units; each backup water supply branch is connected to the outlet of the variable frequency seawater pump in the corresponding DP chain cooling unit, and each backup water supply branch is equipped with a seawater switching valve.

[0009] Optionally, each of the variable frequency seawater pumps is equipped with a pressure detection element at its outlet; the control device is also communicatively connected to the standby variable frequency seawater pump, each of the seawater switching valves and each of the pressure detection elements, and the control device is configured to control the seawater switching valve corresponding to the DP chain cooling unit where the pressure detection element is located to open and start the standby variable frequency seawater pump when the detected pressure of any of the pressure detection elements is lower than the preset pressure.

[0010] Optionally, it also includes a backup freshwater cooling pump; at least two of the freshwater cooling circuits are located in different DP chain cooling units and are respectively used to connect to a corresponding group of cooling users, and the types of each group of cooling users are the same; the backup freshwater cooling pump is shared by at least two of the freshwater cooling circuits and can be selectively connected to any of the freshwater cooling circuits.

[0011] Optionally, the inlet of the standby freshwater cooling pump is connected to multiple standby water inlet branches, and the outlet of the standby freshwater cooling pump is connected to multiple standby water outlet branches; each standby water inlet branch is connected to the inlet of the corresponding freshwater cooling pump, and each standby water outlet branch is connected to the outlet of the corresponding freshwater cooling pump; each standby water inlet branch is equipped with an inlet switching valve, and each standby water outlet branch is equipped with an outlet switching valve.

[0012] Optionally, each of the freshwater cooling pumps is equipped with a freshwater pressure detection device at its outlet. The control device is also communicatively connected to the standby freshwater cooling pump, each of the inlet switching valves, each of the outlet switching valves, and each of the freshwater pressure detection devices. The control device is configured to, when the detected pressure of any of the freshwater pressure detection devices is lower than a preset pressure, control the opening of the inlet switching valve and the outlet switching valve corresponding to the freshwater cooling circuit where the freshwater pressure detection device is located, and control the start of the standby freshwater cooling pump after both the corresponding inlet switching valve and the outlet switching valve are opened.

[0013] Optionally, each of the freshwater cooling circuits further includes a freshwater cooling branch, a freshwater bypass branch, and a three-way temperature control valve; the inlets of the freshwater cooling branch and the freshwater bypass branch are connected to the return water side of the corresponding group of cooling users, and the freshwater channel of the central cooler is located in the freshwater cooling branch; the outlets of the freshwater cooling branch and the freshwater bypass branch are respectively connected to the two inlets of the three-way temperature control valve, and the outlet of the three-way temperature control valve is connected to the inlet of the freshwater cooling pump; the freshwater bypass branch is provided with a bypass regulating orifice plate.

[0014] Another objective of this invention is to provide a control method for a DP ship seawater variable frequency central freshwater cooling system, so as to achieve coordinated regulation of the seawater branch flow rate of each central cooler and the total seawater flow rate of the DP chain cooling unit.

[0015] To achieve this objective, the present invention adopts the following technical solution: This invention also provides a control method for a DP ship seawater variable frequency central freshwater cooling system, applied to the aforementioned DP ship seawater variable frequency central freshwater cooling system. The control method includes: acquiring a first detected temperature detected by each of the first temperature sensors in the target DP chain cooling unit; adjusting the opening of the corresponding flow regulating valve according to the deviation between each of the first detected temperatures and a first preset temperature; acquiring a second detected temperature detected by the second temperature sensor in the target DP chain cooling unit; and adjusting the rotational speed of the variable frequency seawater pump in the target DP chain cooling unit according to the deviation between the second detected temperature and the second preset temperature when the variable frequency seawater pump in the target DP chain cooling unit is operating normally.

[0016] Optionally, each of the first detected temperatures corresponds to a first preset deviation value, and the second detected temperature corresponds to a second preset deviation value. When the absolute value of the deviation between any of the first detected temperatures and the first preset temperature is greater than the corresponding first preset deviation value, the opening of the corresponding flow regulating valve is reduced when the first detected temperature is lower than the first preset temperature, and the opening of the corresponding flow regulating valve is increased when the first detected temperature is higher than the first preset temperature. When the absolute value of the deviation is not greater than the corresponding first preset deviation value, the opening of the corresponding flow regulating valve remains unchanged. When the absolute value of the deviation between the second detected temperature and the second preset temperature is greater than the second preset deviation value, the speed of the variable frequency seawater pump is reduced when the second detected temperature is lower than the second preset temperature, and the speed of the variable frequency seawater pump is increased when the second detected temperature is higher than the second preset temperature. When the absolute value of the deviation is not greater than the second preset deviation value, the speed of the variable frequency seawater pump remains unchanged.

[0017] Optionally, the DP ship seawater variable frequency central freshwater cooling system further includes a backup variable frequency seawater pump and multiple seawater switching valves corresponding one-to-one with the multiple DP chain cooling units; the control method further includes: acquiring the outlet pressure of the variable frequency seawater pump in the target DP chain cooling unit; when the outlet pressure is lower than a preset pressure, opening the seawater switching valve corresponding to the target DP chain cooling unit; after receiving feedback from the opening of the seawater switching valve, starting the backup variable frequency seawater pump; after the backup variable frequency seawater pump starts, switching the control object whose speed is adjusted according to the second detected temperature from the variable frequency seawater pump in the target DP chain cooling unit to the backup variable frequency seawater pump.

[0018] Beneficial effects: The DP ship seawater variable frequency central freshwater cooling system provided by this invention, by setting up DP chain cooling units for each DP chain and setting up multiple independent freshwater cooling circuits in each DP chain cooling unit, can reduce the impact on other cooling users when a single freshwater cooling circuit fails. By adjusting the opening of the corresponding flow regulating valve according to the seawater outlet temperature of each central cooler and adjusting the speed of the variable frequency seawater pump according to the temperature of the seawater collection manifold, it can take into account the cooling needs of each central cooler and the overall seawater flow requirements of the DP chain cooling units, improve the adaptability of seawater flow regulation, and reduce system operating energy consumption.

[0019] The control method of the DP ship seawater variable frequency central freshwater cooling system provided by the present invention can achieve coordinated regulation of seawater branch flow and total seawater flow by adjusting the flow rate of the corresponding seawater supply branch according to the seawater outlet temperature of each central cooler and adjusting the speed of the variable frequency seawater pump according to the temperature of the collected seawater. This allows the seawater supply to adapt to the changes in cooling load of different central coolers and the DP chain as a whole. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the principle of a DP ship seawater frequency conversion central freshwater cooling system according to an embodiment of the present invention.

[0021] In the picture: 100. DP chain cooling unit; 10. Variable frequency seawater pump; 11. Pressure testing components; 20. Freshwater cooling circuit; 21. Freshwater cooling pump; 22. Intercooler; 23. Freshwater pressure sensor; 24. Three-way thermostatic valve; 25. Bypass regulating orifice plate; 30. Seawater supply branch; 31. Flow regulating valve; 32. First temperature sensing element; 33. Second temperature sensing element; 34. Seawater regulating orifice plate; 40. Backup variable frequency seawater pump; 41. Seawater switching valve; 50. Standby freshwater cooling pump; 51. Inlet water switching valve; 52. Outlet water switching valve. Detailed Implementation

[0022] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement the invention, and are not intended to exhaustively describe all possible embodiments of the invention, nor to limit the scope of the invention.

[0023] In the description of the present invention, unless otherwise explicitly specified and limited, the terms "connected", "coupled" and "fixed" shall be construed in a broad sense, for example, they may be fixedly connected, detachably connected, or integrated; they may be mechanically connected, or electrically connected; they may be directly connected, or indirectly connected through an intermediate medium, and may be in an internal communication relationship or interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0024] The present invention will be further described in detail below with reference to the accompanying drawings of the specification and specific embodiments.

[0025] As shown in Figure 1 , an embodiment of the present invention provides a DP ship seawater variable-frequency central fresh water cooling system, which is used for a DP ship with multiple DP chains. A DP chain refers to a set of equipment and its supporting systems that can independently provide dynamic positioning functions for the ship. The equipment in the DP chain may include main generators, propellers, rudder propeller motors, side thruster motors, frequency converters, transformers, and auxiliary equipment supporting the above-mentioned equipment.

[0026] It should be noted that a cooling user refers to an apparatus or component in the DP chain that is connected to the fresh water cooling circuit 20 and needs to be cooled by circulating fresh water, and not all apparatuses in the DP chain belong to cooling users. Specifically, the cooling users may include heat-generating apparatuses such as main generators, rudder propeller motors, side thruster motors, frequency converters and transformers, and may also include heat exchange apparatuses such as lubricating oil coolers, bearing coolers and air conditioning coolers supporting the above-mentioned apparatuses.

[0027] The DP ship seawater variable-frequency central fresh water cooling system includes a control device and a plurality of DP chain cooling units 100 in one-to-one correspondence with the plurality of DP chains. Each DP chain cooling unit 100 includes a variable-frequency seawater pump 10, a seawater collecting main pipe, and a plurality of independent fresh water cooling circuits 20. Each fresh water cooling circuit 20 is configured to communicate with a group of cooling users, and includes a fresh water cooling pump 21 and a central cooler 22. The outlet of the fresh water cooling pump 21 communicates with the water supply side of the corresponding group of cooling users. The central cooler 22 has a fresh water passage and a seawater passage that exchange heat with each other and are isolated from each other, and the fresh water passage is connected to the corresponding fresh water cooling circuit 20.

[0028] A plurality of seawater supply branches 30 are connected to the outlet of the variable-frequency seawater pump 10, and the plurality of seawater supply branches 30 are in one-to-one correspondence with the plurality of central coolers 22. Each seawater supply branch 30 communicates with the inlet of the seawater passage of the corresponding central cooler 22, and is provided with a flow regulating valve 31. The outlets of the seawater passages of each central cooler 22 are all communicated with the seawater collecting main pipe of the same DP chain cooling unit 100, each seawater passage outlet is provided with a first temperature detecting element 32, and the seawater collecting main pipe is provided with a second temperature detecting element 33.

[0029] The control device is communicatively connected to each variable frequency seawater pump 10, each flow regulating valve 31, each first temperature sensor 32, and each second temperature sensor 33. The control device can adjust the opening degree of the corresponding flow regulating valve 31 according to the detected temperature of each first temperature sensor 32, and adjust the speed of the corresponding variable frequency seawater pump 10 according to the detected temperature of each second temperature sensor 33.

[0030] Therefore, different freshwater cooling circuits 20 can cool different groups of cooling users separately, reducing the impact on other cooling users when a single freshwater cooling circuit 20 fails; at the same time, by adjusting the flow rate of the seawater supply branch 30 corresponding to each central cooler 22 and the total seawater flow rate of the DP chain cooling unit 100, the seawater supply can be adapted to changes in cooling load, reducing the operating energy consumption of the variable frequency seawater pump 10.

[0031] To clearly illustrate the main structure of this embodiment, the accompanying drawings only show the main components related to the technical solution of this invention. The freshwater cooling circuit 20 and the seawater supply pipeline may also be equipped with conventional components such as shut-off valves, check valves, filters, expansion tanks, venting devices, and drain devices, as needed; not all of these are shown in the accompanying drawings.

[0032] In this embodiment, "independent configuration" means that each freshwater cooling circuit 20 forms an independent freshwater circulation path and is equipped with a freshwater cooling pump 21 and a central cooler 22 respectively. During normal operation, the different freshwater cooling circuits 20 are isolated from each other. If the freshwater cooling pump 21, central cooler 22 or pipeline in one freshwater cooling circuit 20 fails, it will not affect the normal freshwater circulation in other freshwater cooling circuits 20.

[0033] like Figure 1 As shown, in this embodiment, the inlets of each variable frequency seawater pump 10 and the standby variable frequency seawater pump 40 are connected to the seawater inlet manifold to draw seawater from the seawater inlet manifold.

[0034] See Figure 1 The DP vessel has two DP chains, each corresponding to a DP chain cooling unit 100. Each DP chain cooling unit 100 includes two freshwater cooling circuits 20, and each freshwater cooling circuit 20 includes a central cooler 22 and two cooling users. The above quantities are for illustrative purposes only. In other embodiments, the number of DP chains, freshwater cooling circuits 20, and cooling users can be adjusted according to the vessel's equipment configuration.

[0035] Each freshwater cooling circuit 20 forms an independent freshwater circulation path and is equipped with a freshwater cooling pump 21 and a central cooler 22. During normal operation, the different freshwater cooling circuits 20 are isolated from each other. A failure in the freshwater cooling pump 21, central cooler 22, or piping of one freshwater cooling circuit 20 will not affect the normal freshwater circulation in other freshwater cooling circuits 20. The seawater supply piping of different DP chain cooling units 100 is also isolated from each other during normal operation.

[0036] Specifically, cooling users in each DP chain can be grouped according to equipment type, operational relevance, and cooling requirements. For example, each main generator and its auxiliary equipment such as oil cooler and bearing cooler can form one group of cooling users; each propeller motor and its propeller inverter, propeller transformer, and air conditioning equipment can form another group of cooling users; each thrust motor and its thrust inverter, thrust transformer, and air conditioning equipment can also form a group of cooling users. Daily transformers, other inverters, DP room air conditioners, and operating equipment can be incorporated into the above groups according to actual cooling requirements, or they can form a separate group of cooling users.

[0037] See Figure 1 In this embodiment, each freshwater cooling circuit 20 further includes a freshwater cooling branch, a freshwater bypass branch, and a three-way thermostatic valve 24. The inlets of both the freshwater cooling branch and the freshwater bypass branch are connected to the return water side of the corresponding group of cooling users. The freshwater passage of the central cooler 22 is located in the freshwater cooling branch. The outlet of the freshwater cooling branch is connected to one inlet of the three-way thermostatic valve 24, the outlet of the freshwater bypass branch is connected to the other inlet of the three-way thermostatic valve 24, the outlet of the three-way thermostatic valve 24 is connected to the inlet of the freshwater cooling pump 21, and the outlet of the freshwater cooling pump 21 is connected to the water supply side of the corresponding group of cooling users.

[0038] During operation, the high-temperature freshwater discharged by the cooling user is divided into two streams. One stream enters the freshwater channel of the central cooler 22 and exchanges heat with the seawater flowing through the seawater channel; the other stream flows through a freshwater bypass branch and does not pass through the central cooler 22. The two streams of freshwater mix at the three-way thermostatic valve 24, which adjusts the mixing ratio of the two streams to ensure that the freshwater flowing to the freshwater cooling pump 21 reaches the set temperature. As the heat load of the cooling user increases, the three-way thermostatic valve 24 gradually increases the proportion of freshwater flowing through the central cooler 22; under higher heat loads, all or most of the freshwater can flow through the central cooler 22.

[0039] Furthermore, the freshwater bypass branch is equipped with a bypass regulating orifice plate 25. The bypass regulating orifice plate 25 is used to adjust the flow resistance of the freshwater bypass branch, so that the freshwater cooling branch and the freshwater bypass branch have a suitable basic flow distribution. The central cooler 22 can be a plate heat exchanger, or other heat exchangers that can exchange heat between freshwater and seawater while isolating them from each other.

[0040] In this embodiment, the three-way thermostatic valve 24 has an opening feedback function, and the control device can obtain the opening state of the three-way thermostatic valve 24 to determine whether the passage from the three-way thermostatic valve 24 to the intercooler 22 is fully open. Optionally, the three-way thermostatic valve 24 can also be equipped with a position detection element for outputting a fully open state signal.

[0041] like Figure 1 As shown, on the seawater side, the variable frequency seawater pump 10 in each DP chain cooling unit 100 is used to supply seawater to multiple central coolers 22 within the DP chain cooling unit 100. The seawater enters the seawater channel of the corresponding central cooler 22 through each seawater supply branch 30, and after heat exchange is completed, it flows into the seawater collection manifold and is discharged overboard through the overboard discharge pipe.

[0042] Both the first temperature sensor 32 and the second temperature sensor 33 can be temperature sensors. Each first temperature sensor 32 is used to detect the seawater outlet temperature of the corresponding intercooler 22, and the second temperature sensor 33 is used to detect the temperature of the seawater discharged from different intercoolers 22 after they merge.

[0043] Optionally, each central cooler 22 may also be equipped with a seawater regulating orifice plate 34 at its seawater outlet. During the initial commissioning of the system, the pipe resistance of each seawater branch can be adjusted by adjusting the orifice diameter of the seawater regulating orifice plate 34, so that the seawater flow through different central coolers 22 is close to the corresponding design flow.

[0044] To ensure that the seawater discharged from each central cooler 22 is fully mixed before temperature detection, a second temperature sensor 33 is positioned downstream of the collection point. In this embodiment, the distance between the second temperature sensor 33 and the collection point is not less than 15 times the diameter of the seawater collection manifold. In other embodiments, this distance can be determined based on the diameter of the seawater collection manifold, the seawater flow velocity, and the pipeline layout.

[0045] In this embodiment, the control device may include a monitoring and alarm control system, a valve remote control system, and a frequency conversion control system. The monitoring and alarm control system is used to receive detection signals, execute control logic, and send control commands; the valve remote control system is used to adjust the flow regulating valve 31, the seawater switching valve 41, the inlet switching valve 51, and the outlet switching valve 52; and the frequency conversion control system is used to adjust the speed of the variable frequency seawater pump 10. Optionally, a central control system can be used to uniformly perform detection, calculation, and command transmission, with the valve remote control system and the frequency conversion control system serving as execution systems respectively.

[0046] Furthermore, the DP shipboard seawater variable frequency central freshwater cooling system also includes a backup variable frequency seawater pump 40 shared by multiple DP chain cooling units 100. The outlet of the backup variable frequency seawater pump 40 is connected to multiple backup water supply branches, each corresponding to one of the multiple DP chain cooling units 100. Each backup water supply branch is connected to the outlet of the variable frequency seawater pump 10 in the corresponding DP chain cooling unit 100 and is equipped with a seawater switching valve 41.

[0047] During normal operation, the seawater switching valves 41 on each standby water supply branch are closed, isolating the seawater pipelines of different DP chain cooling units 100 from each other. When any variable frequency seawater pump 10 fails, or when the crew needs to actively use the standby variable frequency seawater pump 40 to replace any variable frequency seawater pump 10, the seawater switching valve 41 corresponding to the target DP chain cooling unit 100 is opened, allowing the standby variable frequency seawater pump 40 to be connected to the target DP chain cooling unit 100.

[0048] In this embodiment, each variable frequency seawater pump 10 is equipped with a pressure detection element 11 at its outlet. The pressure detection element 11 can be a pressure switch or a pressure sensor. The control device is communicatively connected to the standby variable frequency seawater pump 40, each seawater switching valve 41, and each pressure detection element 11.

[0049] When any pressure sensor 11 detects that the outlet pressure of the variable frequency seawater pump 10 is lower than the preset pressure, the control device opens the seawater switching valve 41 corresponding to the DP chain cooling unit 100 where the variable frequency seawater pump 10 is located. After receiving the opening feedback of the seawater switching valve 41, the control device starts the standby variable frequency seawater pump 40 and outputs a fault alarm signal for the corresponding variable frequency seawater pump 10.

[0050] After the standby variable frequency seawater pump 40 starts, the control device adjusts the speed of the standby variable frequency seawater pump 40 according to the temperature detected by the second temperature sensor 33 in the target DP chain cooling unit 100, so that the standby variable frequency seawater pump 40 takes over from the faulty variable frequency seawater pump 10 and supplies seawater to each central cooler 22 in the target DP chain cooling unit 100. A pressure sensor 11 can also be installed at the outlet of the standby variable frequency seawater pump 40 to output a fault alarm signal when its outlet pressure is insufficient.

[0051] When a crew member actively uses the backup variable frequency seawater pump 40 to replace any variable frequency seawater pump 10, they can also open the seawater switching valve 41 corresponding to the target DP chain cooling unit 100 and make the backup variable frequency seawater pump 40 adjust the frequency according to the temperature detected by the second temperature detection element 33 in the target DP chain cooling unit 100.

[0052] It is understandable that multiple DP chain cooling units 100 share a single standby variable frequency seawater pump 40, which can reduce the number of standby seawater pumps and the space occupied by the equipment; by selectively connecting the standby variable frequency seawater pump 40 to the target DP chain cooling unit 100 through the seawater switching valve 41, the different DP chains can be kept isolated from each other during normal operation.

[0053] Furthermore, the DP marine seawater variable frequency central freshwater cooling system also includes a backup freshwater cooling pump 50. At least two freshwater cooling loops 20 located in different DP chain cooling units 100 and used to cool the same type of cooling users share a backup freshwater cooling pump 50.

[0054] The inlet of the standby freshwater cooling pump 50 is connected to multiple standby water inlet branches, each of which is connected to the inlet of the corresponding freshwater cooling pump 21. Each standby water inlet branch is equipped with an inlet switching valve 51. The outlet of the standby freshwater cooling pump 50 is connected to multiple standby water outlet branches, each of which is connected to the outlet of the corresponding freshwater cooling pump 21. Each standby water outlet branch is equipped with an outlet switching valve 52.

[0055] In this embodiment, the two freshwater cooling circuits 20 corresponding to the first type of cooling user in the two DP chains share one spare freshwater cooling pump 50, and the two freshwater cooling circuits 20 corresponding to the second type of cooling user in the two DP chains share another spare freshwater cooling pump 50. Therefore, this embodiment is equipped with two spare freshwater cooling pumps 50.

[0056] During normal operation, the inlet switching valve 51 on each standby inlet branch and the outlet switching valve 52 on each standby outlet branch are all in the closed state. Each freshwater cooling pump 21 is equipped with a freshwater pressure detection element 23 at its outlet; the freshwater pressure detection element 23 can be a pressure switch or a pressure sensor. The control device is communicatively connected to the standby freshwater cooling pump 50, each inlet switching valve 51, each outlet switching valve 52, and each freshwater pressure detection element 23.

[0057] When any freshwater pressure sensor 23 detects that the outlet pressure of the corresponding freshwater cooling pump 21 is lower than the preset pressure, the control device opens the inlet switching valve 51 and the outlet switching valve 52 corresponding to the freshwater cooling circuit 20 where that freshwater cooling pump 21 is located, while the remaining inlet switching valves 51 and the outlet switching valves 52 remain closed. After receiving feedback from the opening of the corresponding inlet switching valve 51 and the outlet switching valve 52, the control device starts the standby freshwater cooling pump 50 and outputs a fault alarm signal for the corresponding freshwater cooling pump 21.

[0058] Optionally, a freshwater pressure sensor 23 can also be installed at the outlet of the standby freshwater cooling pump 50 to detect whether the standby freshwater cooling pump 50 has established outlet pressure normally. By allowing the standby freshwater cooling pump 50 to be shared by the same type of freshwater cooling circuit 20 in different DP chains, the redundancy of the freshwater cooling pump 21 can be guaranteed while reducing the number of standby pumps.

[0059] It should be noted that, in addition to the components mentioned above, Figure 1 Other conventional components such as valves, pumps, filters, measuring instruments, and pipeline accessories are also shown. These components can be set according to actual usage requirements, and their specific types, quantities, and locations do not constitute a limitation on the present invention.

[0060] In summary, the DP ship seawater variable frequency central freshwater cooling system provided in this embodiment reduces the impact on other cooling users when a single freshwater cooling circuit 20 fails by setting up DP chain cooling units 100 for multiple DP chains and setting up multiple independent freshwater cooling circuits 20 in each DP chain cooling unit 100. By adjusting the flow rate of the corresponding seawater supply branch 30 according to the seawater outlet temperature of each central cooler 22 and adjusting the speed of the variable frequency seawater pump 10 according to the seawater temperature in the seawater collection main pipe, the cooling needs of each central cooler 22 and the overall seawater flow rate needs of the DP chain cooling units 100 can be taken into account. At the same time, by having multiple DP chain cooling units 100 share a backup variable frequency seawater pump 40 and having the same type of freshwater cooling circuit 20 in different DP chains share a backup freshwater cooling pump 50, the number of backup pumps and equipment space occupied can be reduced while ensuring cooling redundancy, thereby improving the reliability, adaptability and operating economy of the DP ship cooling system.

[0061] This embodiment also provides a control method for the above-mentioned DP ship seawater frequency conversion central freshwater cooling system.

[0062] During operation, the control device acquires the first detected temperature detected by each first temperature sensor 32 in the target DP chain cooling unit 100, and adjusts the opening of the corresponding flow regulating valve 31 according to the deviation between each first detected temperature and a first preset temperature. The control device also acquires the second detected temperature detected by the second temperature sensor 33 in the target DP chain cooling unit 100. When the variable frequency seawater pump 10 in the target DP chain cooling unit 100 is operating normally, the control device adjusts the speed of the variable frequency seawater pump 10 according to the deviation between the second detected temperature and the second preset temperature.

[0063] Specifically, each first detected temperature corresponds to a first preset deviation value. When the absolute value of the deviation between any first detected temperature and the first preset temperature is greater than the corresponding first preset deviation value, if the first detected temperature is lower than the first preset temperature, the control device reduces the opening of the corresponding flow regulating valve 31 to reduce the seawater flow through the corresponding central cooler 22; if the first detected temperature is higher than the first preset temperature, the control device increases the opening of the corresponding flow regulating valve 31. When the absolute value of the deviation between the first detected temperature and the first preset temperature is not greater than the corresponding first preset deviation value, the control device keeps the opening of the corresponding flow regulating valve 31 unchanged.

[0064] The second detected temperature corresponds to a second preset deviation value. When the absolute value of the deviation between the second detected temperature and the second preset temperature is greater than the second preset deviation value, if the second detected temperature is lower than the second preset temperature, the control device reduces the speed of the variable frequency seawater pump 10 to reduce the total seawater flow of the target DP chain cooling unit 100; if the second detected temperature is higher than the second preset temperature, the control device increases the speed of the variable frequency seawater pump 10. When the absolute value of the deviation between the second detected temperature and the second preset temperature is not greater than the second preset deviation value, the control device keeps the speed of the variable frequency seawater pump 10 constant.

[0065] By setting a first preset deviation value and a second preset deviation value, a control range that allows temperature fluctuations without triggering regulation can be formed, reducing the frequent operation of the flow regulating valve 31 and the variable frequency seawater pump 10 caused by small temperature fluctuations.

[0066] In this embodiment, the set temperature of the three-way thermostatic valve 24 is defined as A, and both the first preset temperature and the second preset temperature are set to A. The seawater temperature difference corresponding to 10% of the heat load of any central cooler 22 under the design seawater flow rate is defined as B, and the corresponding first preset deviation value is set to B / 2; the seawater temperature difference corresponding to 10% of the total heat load of all central coolers 22 in the same DP chain cooling unit 100 under the design seawater flow rate is defined as C, and the second preset deviation value is set to C / 2.

[0067] B and C can be calculated based on the following relationship: Where Q is the heat exchange load. The mass flow rate of seawater. Let ΔT be the specific heat capacity of seawater, and ΔT be the temperature difference of seawater. The mass flow rate of seawater can be calculated based on the volumetric flow rate and density of seawater. The density and specific heat capacity of seawater can be selected based on the design seawater temperature and salinity.

[0068] Since the design heat load and design seawater flow rate of different central coolers 22 may be different, the B and the first preset deviation value corresponding to each central cooler 22 may also be different.

[0069] For example, the design flow rate of the variable frequency seawater pump 10 is 480 m³ / h. 3 / h (cubic meters per hour), with a design outlet pressure of 0.25MPa; the design heat loads of the two central coolers 22 are 3000kW and 550kW respectively, corresponding to design seawater flow rates of 320m³ / h and 320m³ / h respectively. 3 / h and 160m 3 / h; The set temperature A of the three-way thermostatic valve 24 is 38℃.

[0070] In this embodiment, the fresh water flowing into the central cooler 22 is high-temperature fresh water discharged by the user, and its temperature is typically higher than the set temperature of the three-way thermostatic valve 24. When the central cooler 22 uses a plate heat exchanger, it has high heat exchange efficiency, and the seawater flowing through the seawater channel can be heated to near or reach the set temperature A. Therefore, using A as the first preset temperature and the second preset temperature allows for a unified temperature control benchmark, balancing cooling capacity and operating energy consumption. In other embodiments, the first preset temperature and the second preset temperature can also be set separately according to the heat exchange performance and cooling load of the central cooler 22.

[0071] Calculations show that the temperature B for the central cooler 22 with a design heat load of 3000kW is 0.88℃, with a first preset deviation of 0.44℃; the temperature B for the central cooler 22 with a design heat load of 550kW is 0.32℃, with a first preset deviation of 0.16℃. The total design heat load of the two central coolers 22 is 3550kW, with a corresponding temperature C of 0.68℃ and a second preset deviation of 0.34℃.

[0072] Therefore, for the central cooler 22 with a design heat load of 3000kW, when the absolute value of the deviation between the first detected temperature and the first preset temperature is not greater than 0.44℃, the opening of the corresponding flow regulating valve 31 is kept unchanged; for the central cooler 22 with a design heat load of 550kW, when the absolute value of the deviation between the first detected temperature and the first preset temperature is not greater than 0.16℃, the opening of the corresponding flow regulating valve 31 is kept unchanged; when the absolute value of the deviation between the second detected temperature and the second preset temperature is not greater than 0.34℃, the speed of the variable frequency seawater pump 10 is kept unchanged.

[0073] Before system startup, the variable frequency control system is in automatic control mode. After receiving the ready-to-operate signal, the control device adjusts each flow regulating valve 31 to its maximum opening and makes the variable frequency seawater pump 10 operate at the minimum allowable speed. In this embodiment, the speed regulation range of the variable frequency seawater pump 10 is 40% to 100% of the rated speed.

[0074] When none of the three-way temperature control valves 24 in the same DP chain cooling unit 100 are fully open to the central cooler 22, the variable frequency seawater pump 10 maintains the minimum allowable speed; when any three-way temperature control valve 24 is fully open to the central cooler 22, the control device adjusts the speed of the variable frequency seawater pump 10 according to the second detected temperature.

[0075] When the control device detects that the inverter of the variable frequency seawater pump 10 is in bypass mode, it adjusts each flow regulating valve 31 in the corresponding DP chain cooling unit 100 to its maximum opening. When a communication failure occurs between the monitoring alarm control system and the valve remote control system or the variable frequency control system, it adjusts each flow regulating valve 31 to its maximum opening and makes the variable frequency seawater pump 10 run at its maximum permissible speed. The above control method can prioritize the seawater supply capacity when the variable frequency control or communication is abnormal.

[0076] The control method in this embodiment also includes the takeover control of the standby variable frequency seawater pump 40. During operation, the control device obtains the outlet pressure of the variable frequency seawater pump 10 in the target DP chain cooling unit 100 through the pressure detection element 11. When the outlet pressure is lower than the preset pressure, the control device opens the seawater switching valve 41 corresponding to the target DP chain cooling unit 100; after receiving the opening feedback of the seawater switching valve 41, the control device starts the standby variable frequency seawater pump 40.

[0077] After the standby variable frequency seawater pump 40 is started, the control device will switch the control object that adjusts the speed according to the second detected temperature from the variable frequency seawater pump 10 in the target DP chain cooling unit 100 to the standby variable frequency seawater pump 40, and adjust the speed of the standby variable frequency seawater pump 40 according to the deviation between the second detected temperature and the second preset temperature, so that the standby variable frequency seawater pump 40 takes over from the variable frequency seawater pump 10 to supply seawater to the target DP chain cooling unit 100.

[0078] For example, the preset pressures of the pressure detection device 11 at the outlet of the variable frequency seawater pump 10, the freshwater pressure detection device 23 at the outlet of the freshwater cooling pump 21, the pressure detection device 11 at the outlet of the standby variable frequency seawater pump 40, and the freshwater pressure detection device 23 at the outlet of the standby freshwater cooling pump 50 can all be set to 0.1 MPa. In other embodiments, the above-mentioned preset pressures can be adjusted according to the design outlet pressure of the corresponding pump and the pipeline resistance.

[0079] In summary, this embodiment improves the cooling independence and redundancy of the DP ship cooling system by setting up DP chain cooling units 100 corresponding to each DP chain, independent freshwater cooling circuits 20, seawater supply branch 30 with flow regulation and frequency conversion regulation of total seawater flow, and configuring a shared backup pump on the seawater side and the freshwater side. This allows the seawater supply to adapt to changes in cooling load and reduces the number of pumps and operating energy consumption.

[0080] It is understood that in this invention, when the number of components or members is not specifically limited, the number can be one or more, where multiple refers to two or more. For cases where the number of components or members shown in the drawings and / or described in the specification is, for example, two, three, four, etc., this specific number is generally exemplary and not limiting, and can be understood as multiple, i.e., two or more; however, this does not mean that the invention excludes the case of one.

[0081] It should be understood that the above-described embodiments, examples, or examples are merely exemplary and are not intended to limit the present invention. Those skilled in the art can make various modifications and changes to the above-described embodiments, examples, or examples under the guidance of the present invention, without departing from the scope of the present invention.

Claims

1. A DP (Digital Digitization) ship seawater variable frequency central freshwater cooling system, used in DP ships with multiple DP chains, characterized in that, Includes a control device and multiple DP chain cooling units (100) corresponding one-to-one with the multiple DP chains. Each of the DP chain cooling units (100) includes a variable frequency seawater pump (10), a seawater collection manifold, and multiple freshwater cooling circuits (20) that are independently set up. Each freshwater cooling circuit (20) is used to connect to a group of cooling users and includes a freshwater cooling pump (21) and a central cooler (22). The outlet of the freshwater cooling pump (21) is connected to the water supply side of the corresponding group of cooling users. The central cooler (22) has a freshwater channel and a seawater channel that exchange heat with each other. The freshwater channel is connected to the corresponding freshwater cooling circuit (20). The outlet of the variable frequency seawater pump (10) is connected to multiple seawater supply branches (30), and the multiple seawater supply branches (30) correspond one-to-one with the multiple central coolers (22). Each seawater supply branch (30) is connected to the inlet of the seawater channel of the corresponding central cooler (22), and each seawater supply branch (30) is equipped with a flow regulating valve (31). The outlet of the seawater channel of each of the central coolers (22) is connected to the seawater collection manifold of the same DP chain cooling unit (100). The outlet of each of the seawater channels is provided with a first temperature detection element (32), and the seawater collection manifold is provided with a second temperature detection element (33). The control device is communicatively connected to each of the variable frequency seawater pumps (10), each of the flow regulating valves (31), each of the first temperature detectors (32) and each of the second temperature detectors (33). The control device is configured to adjust the opening degree of the corresponding flow regulating valve (31) according to the detected temperature of each of the first temperature detectors (32), and to adjust the rotation speed of the corresponding variable frequency seawater pump (10) according to the detected temperature of each of the second temperature detectors (33).

2. The DP marine seawater frequency conversion central freshwater cooling system according to claim 1, characterized in that, It also includes a backup variable frequency seawater pump (40) shared by multiple DP chain cooling units (100); the outlet of the backup variable frequency seawater pump (40) is connected to multiple backup water supply branches, and the multiple backup water supply branches correspond one-to-one with the multiple DP chain cooling units (100); Each of the backup water supply branches is connected to the outlet of the variable frequency seawater pump (10) in the corresponding DP chain cooling unit (100), and each of the backup water supply branches is equipped with a seawater switching valve (41).

3. The DP marine seawater frequency conversion central freshwater cooling system according to claim 2, characterized in that, Each of the aforementioned variable frequency seawater pumps (10) is equipped with a pressure detection element (11) at its outlet. The control device is also connected in communication with the standby variable frequency seawater pump (40), each of the seawater switching valves (41) and each of the pressure detection devices (11). The control device is configured to open the seawater switching valve (41) corresponding to the DP chain cooling unit (100) where the pressure detection device (11) is located when the detection pressure of any of the pressure detection devices (11) is lower than the preset pressure, and start the standby variable frequency seawater pump (40).

4. The DP marine seawater frequency conversion central freshwater cooling system according to claim 1, characterized in that, It also includes a backup freshwater cooling pump (50); At least two of the freshwater cooling circuits (20) are located in different DP chain cooling units (100) and are respectively used to connect to a corresponding group of cooling users, and the types of the cooling users in each group are the same; The standby freshwater cooling pump (50) is shared by at least two of the freshwater cooling circuits (20) and can be selectively connected to any of the freshwater cooling circuits (20).

5. The DP marine seawater frequency conversion central freshwater cooling system according to claim 4, characterized in that, The inlet of the standby freshwater cooling pump (50) is connected to multiple standby water inlet branches, and the outlet of the standby freshwater cooling pump (50) is connected to multiple standby water outlet branches. Each of the backup water inlet branches is connected to the inlet of the corresponding fresh water cooling pump (21), and each of the backup water outlet branches is connected to the outlet of the corresponding fresh water cooling pump (21); each of the backup water inlet branches is equipped with an inlet switching valve (51), and each of the backup water outlet branches is equipped with an outlet switching valve (52).

6. The DP marine seawater frequency conversion central freshwater cooling system according to claim 5, characterized in that, Each of the fresh water cooling pumps (21) is equipped with a fresh water pressure detection device (23) at its outlet. The control device is also connected in communication with the standby fresh water cooling pump (50), each of the inlet switching valves (51), each of the outlet switching valves (52) and each of the fresh water pressure detection devices (23). The control device is configured to, when the detection pressure of any of the freshwater pressure detection devices (23) is lower than the preset pressure, control the opening of the inlet switching valve (51) and the outlet switching valve (52) corresponding to the freshwater cooling circuit (20) where the freshwater pressure detection device (23) is located, and control the start of the standby freshwater cooling pump (50) after the corresponding inlet switching valve (51) and the outlet switching valve (52) are both opened.

7. The DP marine seawater frequency conversion central freshwater cooling system according to any one of claims 1 to 6, characterized in that, Each of the freshwater cooling circuits (20) also includes a freshwater cooling branch, a freshwater bypass branch, and a three-way thermostatic valve (24). The inlets of the freshwater cooling branch and the freshwater bypass branch are connected to the return water side of the corresponding group of cooling users. The freshwater channel of the central cooler (22) is located in the freshwater cooling branch. The outlets of the freshwater cooling branch and the freshwater bypass branch are connected to the two inlets of the three-way temperature control valve (24). The outlet of the three-way temperature control valve (24) is connected to the inlet of the freshwater cooling pump (21). The freshwater bypass branch is equipped with a bypass regulating orifice plate (25).

8. A control method for a DP ship seawater variable frequency central freshwater cooling system, applied to the DP ship seawater variable frequency central freshwater cooling system according to any one of claims 1 to 7, characterized in that, The control method includes: The first detection temperature detected by each of the first temperature detection elements (32) in the target DP chain cooling unit (100) is obtained, and the opening degree of the corresponding flow regulating valve (31) is adjusted according to the deviation between each of the first detection temperatures and the first preset temperature. Obtain the second detection temperature detected by the second temperature detection element (33) in the target DP chain cooling unit (100); When the variable frequency seawater pump (10) in the target DP chain cooling unit (100) is running normally, the speed of the variable frequency seawater pump (10) in the target DP chain cooling unit (100) is adjusted according to the deviation between the second detected temperature and the second preset temperature.

9. The control method for the DP ship seawater variable frequency central freshwater cooling system according to claim 8, characterized in that, Each of the first detected temperatures corresponds to a first preset deviation value, and each of the second detected temperatures corresponds to a second preset deviation value. When the absolute value of the deviation between any of the first detected temperatures and the first preset temperature is greater than the corresponding first preset deviation value, the opening of the corresponding flow regulating valve (31) is reduced when the first detected temperature is lower than the first preset temperature, and the opening of the corresponding flow regulating valve (31) is increased when the first detected temperature is higher than the first preset temperature; when the absolute value of the deviation is not greater than the corresponding first preset deviation value, the opening of the corresponding flow regulating valve (31) is kept unchanged. When the absolute value of the deviation between the second detected temperature and the second preset temperature is greater than the second preset deviation value, the speed of the variable frequency seawater pump (10) is reduced when the second detected temperature is lower than the second preset temperature, and the speed of the variable frequency seawater pump (10) is increased when the second detected temperature is higher than the second preset temperature; when the absolute value of the deviation is not greater than the second preset deviation value, the speed of the variable frequency seawater pump (10) is kept constant.

10. The control method for the DP ship seawater variable frequency central freshwater cooling system according to claim 8, characterized in that, The DP ship seawater variable frequency central freshwater cooling system also includes a backup variable frequency seawater pump (40) and multiple seawater switching valves (41) corresponding one-to-one with the multiple DP chain cooling units (100); the control method also includes: Obtain the outlet pressure of the variable frequency seawater pump (10) in the target DP chain cooling unit (100); When the outlet pressure is lower than the preset pressure, the seawater switching valve (41) corresponding to the target DP chain cooling unit (100) is opened. After receiving feedback from the opening of the seawater switching valve (41), the standby variable frequency seawater pump (40) is started. After the standby variable frequency seawater pump (40) is started, the control object that adjusts the speed according to the second detected temperature will be switched from the variable frequency seawater pump (10) in the target DP chain cooling unit (100) to the standby variable frequency seawater pump (40).

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